The pathogenesis, molecular biology, immunology, natural history, and therapy of human herpes virus infections are being investigated. Immunocompetent and immunodeficient patients with a wide range of herpesvirus infections have been identified, followed clinically, diagnosed by virus isolation, and studied immunologically. During the past year we have made major advances in the treatment and suppression of herpes simplex infections using acyclovir. Our major focus on the study of the molecular biology and latency of varicella zoster virus (VZV) DNA has continued. We have completed restriction endonuclease analyses and molecular epidemiologic studies of 26 strains of VZV DNA and have completed the mapping of the VZV genome. We are now using these recombinant clones for rapid diagnosis of varicella and zoster infections and as probes of human tissues to determine the sites and nature of viral latency. In the coming year we will initiate studies of the genetic expression of VZV.